Final answer:
The command 'chmod o-w datafile' removes write permission for users who are not the owner or part of the group associated with the file named 'datafile'.
Step-by-step explanation:
The command chmod o-w datafile is used in Unix and Unix-like operating systems to modify the permissions of a file or directory. Specifically, this command removes write permission for others from the file named 'datafile'. This means that users who are not the owner of the file or members of the file's group will no longer have permission to modify ('write' to) the file. The command does not affect write permission for the user (owner) or the group associated with the file, and it does not set or modify any other permissions.